DESCRIPTION: This proposal is based on a novel model system developed and optimized in Dr. Reddy's laboratory which offers an unique opportunity to: (1) investigate the mechanistic role of copper-deficiency in the near-global pancreatic acinar cell loss, which appears to unmask and trigger a proliferative response of cells which then differentiate into pancreatic hepatocytes; (b) examine the e xistence of "stem cells" or "uncommitted" bipotential cells in the adult pancreas that can differentiate into hepatocytes with morphological and functional properties similar to those of hepatic parenchymal cells of liver; and (c) explore the differentiation potential of these uncommitted cells under in vivo and in vitro conditions into hepatocytes, pancreatic ductal, acinar or other types of cells. Two major hypothesis form the basis of studies proposed in this competing renewal application: (1) that copper-deficiency induces oxidative damage in adult pancreatic acinar cells by reducing the levels of expression of antioxidant enzyme genes, and the resultant oxidant damage leads to apoptotic death of acinar cells; and (2) that bi (multi)-potential progenitor cells (stem cells) exist, but remain dormant, in the normal adult pancreas, and that they proliferate and follow hapatocyte differentiation lineage due to an obscure "stimulus" provided by the global acinar cell loss. This differentiation process is reminiscent of that occurring during early embryonic development where hepatocytes and pancreas emerge from the same primordium. Our objectives of the proposed research are to: 1. investigate the mechanism(s) by which copper-deficiency causes apoptosis of acinar cells in the rat pancreas: (a) by examining the expression of genes involved in apoptosis; and (b) by investigating the changes in antioxidant enzyme expression and the oxidant stress due to the generation of reactive oxygen species; 2. identify uncommitted cells by localizing NFxB, stem cell factor, c-kit, hepatocyte nuclear factor and other early hepatocyte markers, and study the hepatocyte lineage in the pancreas of copper deficient rats in vivo using retroviral mediated beta- galactosidase gene transfer; 3. delineate the proliferative and morphogenetic responses of pancreatic oval cells and duct cells isolated from copper-deficient rats malignant transformation in oval cells in an attempt to generate hepatocellular carcinomas, adenocarcinomas with pancreatic ductal-phenotype, or acinar cell carcinomas; and 5. identify novel cellular responses in pancreas following copper-deficiency by utilizing two-dimensional electrophoresis and differential gene expression techniques. These studies will generate information of a fundamental nature about the molecular mechanisms of copper-deficiency induced apoptotic cell death and the events that trigger changes in cell commitment and differentiation. The copper deficiency model is better suited than the existing liver oval cell systems for the isolation of liver stem cells because in the normal pancreas, there are no hepatocytes to confound the observations.